[Internal] Remove dependency to the `openapi` package of the Go SDK (#1676)

## Changes

This PR removes the dependency to the `databricks-sdk-go/openapi`
package by copying the struct and functions that are needed in a new
`schema/spec.go` file.

The reason to remove this dependency is that it is being deprecated.
Copying the code in the `cli` repo seems reasonable given that it only
uses a couple of very small structs.

## Tests

Verified that CLI code can be properly generated after this change.

bundle/schema/docs.go

@@ -9,7 +9,6 @@ import (
 
 	"github.com/databricks/cli/bundle/config"
 	"github.com/databricks/cli/libs/jsonschema"
-	"github.com/databricks/databricks-sdk-go/openapi"
 )
 
 // A subset of Schema struct
@@ -63,7 +62,7 @@ func UpdateBundleDescriptions(openapiSpecPath string) (*Docs, error) {
 	if err != nil {
 		return nil, err
 	}
-	spec := &openapi.Specification{}
+	spec := &Specification{}
 	err = json.Unmarshal(openapiSpec, spec)
 	if err != nil {
 		return nil, err

bundle/schema/openapi.go

@@ -6,12 +6,11 @@ import (
 	"strings"
 
 	"github.com/databricks/cli/libs/jsonschema"
-	"github.com/databricks/databricks-sdk-go/openapi"
 )
 
 type OpenapiReader struct {
 	// OpenAPI spec to read schemas from.
-	OpenapiSpec *openapi.Specification
+	OpenapiSpec *Specification
 
 	// In-memory cache of schemas read from the OpenAPI spec.
 	memo map[string]jsonschema.Schema

bundle/schema/openapi_test.go

@@ -5,7 +5,6 @@ import (
 	"testing"
 
 	"github.com/databricks/cli/libs/jsonschema"
-	"github.com/databricks/databricks-sdk-go/openapi"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -45,7 +44,7 @@ func TestReadSchemaForObject(t *testing.T) {
 		}
 	}
 	`
-	spec := &openapi.Specification{}
+	spec := &Specification{}
 	reader := &OpenapiReader{
 		OpenapiSpec: spec,
 		memo:        make(map[string]jsonschema.Schema),
@@ -103,7 +102,7 @@ func TestReadSchemaForArray(t *testing.T) {
 			}
 		}
 	}`
-	spec := &openapi.Specification{}
+	spec := &Specification{}
 	reader := &OpenapiReader{
 		OpenapiSpec: spec,
 		memo:        make(map[string]jsonschema.Schema),
@@ -149,7 +148,7 @@ func TestReadSchemaForMap(t *testing.T) {
 			}
 		}
 	}`
-	spec := &openapi.Specification{}
+	spec := &Specification{}
 	reader := &OpenapiReader{
 		OpenapiSpec: spec,
 		memo:        make(map[string]jsonschema.Schema),
@@ -198,7 +197,7 @@ func TestRootReferenceIsResolved(t *testing.T) {
 			}
 		}
 	}`
-	spec := &openapi.Specification{}
+	spec := &Specification{}
 	reader := &OpenapiReader{
 		OpenapiSpec: spec,
 		memo:        make(map[string]jsonschema.Schema),
@@ -248,7 +247,7 @@ func TestSelfReferenceLoopErrors(t *testing.T) {
 			}
 		}
 	}`
-	spec := &openapi.Specification{}
+	spec := &Specification{}
 	reader := &OpenapiReader{
 		OpenapiSpec: spec,
 		memo:        make(map[string]jsonschema.Schema),
@@ -282,7 +281,7 @@ func TestCrossReferenceLoopErrors(t *testing.T) {
 			}
 		}
 	}`
-	spec := &openapi.Specification{}
+	spec := &Specification{}
 	reader := &OpenapiReader{
 		OpenapiSpec: spec,
 		memo:        make(map[string]jsonschema.Schema),
@@ -327,7 +326,7 @@ func TestReferenceResolutionForMapInObject(t *testing.T) {
 			}
 		}
 	}`
-	spec := &openapi.Specification{}
+	spec := &Specification{}
 	reader := &OpenapiReader{
 		OpenapiSpec: spec,
 		memo:        make(map[string]jsonschema.Schema),
@@ -397,7 +396,7 @@ func TestReferenceResolutionForArrayInObject(t *testing.T) {
 			}
 		}
 	}`
-	spec := &openapi.Specification{}
+	spec := &Specification{}
 	reader := &OpenapiReader{
 		OpenapiSpec: spec,
 		memo:        make(map[string]jsonschema.Schema),
@@ -460,7 +459,7 @@ func TestReferenceResolutionDoesNotOverwriteDescriptions(t *testing.T) {
 			}
 		}
 	}`
-	spec := &openapi.Specification{}
+	spec := &Specification{}
 	reader := &OpenapiReader{
 		OpenapiSpec: spec,
 		memo:        make(map[string]jsonschema.Schema),

bundle/schema/spec.go

@@ -0,0 +1,11 @@
+package schema
+
+import "github.com/databricks/cli/libs/jsonschema"
+
+type Specification struct {
+	Components *Components `json:"components"`
+}
+
+type Components struct {
+	Schemas map[string]*jsonschema.Schema `json:"schemas,omitempty"`
+}